Those numbers add up to good news for the ACA, popularly known as Obamacare. So why aren’t Democrats pointing their fingers at Republicans and shouting, “I told you so!” Why aren’t they running on those successes as the mid-term campaigns crank up? And, why aren’t Democrats partying?

House Minority Leader Nancy Pelosi, D-Calif., told Vox in May that Democrats largely consider the ACA a wash. “We’re not running on or from the Affordable Care Act,” she said.

Following the interview with Pelosi, Ezra Klein summed up the view:

If you had told most Democrats in 2010 that by the time the 2014 election rolled around Obamacare would have rolled out with lower premiums and higher enrollment than anyone projected they would have been thrilled. They knew when they passed the law that it was going to be a political loser in the 2010 election but they figured that if they could just get it up-and-running — and insuring millions of people — it would be a winner in future elections. And perhaps it will be. But the definition of “future” keeps getting pushed out. Obamacare is working, but not for Democrats.

You’d be hard-pressed to find a political mid-term ad that uses the ACA as the main reason for voting for a candidate, unless you’re a Republican and the ad attacks the health care law. It’s even harder to find a Democratic ad that mentions the law by name.

But why is that? Now that the act’s results are measurably positive, shouldn’t Democrats embrace it as a political platform?

“It’s a once burned phenomenon,” says Elaine Kamarck, senior fellow at the Brookings Institution. “Everyone thought this would be a triumphant thing — but between the botched roll-out and the people who had their health care plans canceled — those are two embarrassing outcomes.”

In other words, she says, Democrats are wary about jumping on the positive results of the exchange sign-ups.

Kamarck adds that the fact that only 15 percent of the population – the neediest – fully benefit from Obamacare doesn’t make it easy to use it in a stump speech or a campaign ad.

“The number of people affected by this is actually pretty small — contrary to the way Republicans think about it,” she said. “It’s only affecting people who don’t have employer provided coverage — it’s a program that addresses a real need but it’s a real need for a small percentage of the population.”

Bill Burton, a Democratic strategist at Global Strategy Group, puts it this way, “I think in places where health care is the center of the political debate, you will see Democrats saying positive things, but for the most part I think it is less a part of the political conversation as it once was. … I think voters in the middle are coming to terms with the fact that it’s a net positive for the country and aren’t voting based on it.”

In other words, Burton agrees with Pelosi that the ACA is now a political draw.

A March Bloomberg poll showed Burton is probably right. It found that 64 percent of Americans now support the ACA outright or back small changes. That means it’s just not as controversial and not as much of a hot topic.

Still, that could change. As more information is released this year about health insurance exchange sign-ups — especially information about the rates insurance companies will charge in 2015 — we’ll see how the two parties manage their tactics going forward to November.

“Everyone is waiting to see not just what happens with the 15 percent who can buy into Obamacare, but they are waiting to see what happens to the health care system as a whole,” Kamarck said. “If the perception is that the health care system in its entirety is doing better, it will end up being good for the president. If the perception is that it is doing worse, it will be blamed … on the ACA.”